Security firm Incapsula has discovered thousands of small-business and home routers that have been taken over by attackers to create botnets for use in denial-of-service attacks.

Attackers have taken advantage of the relative naïveté of home users and small business owners to compromise tens of thousands of residential routers and use them to inundate corporate websites with floods of data, security firm Imperva stated in an analysis posted on May 12.
The attack took advantage of the default credentials in a widely used model of router made by Ubiquiti, a manufacturer of technology for emerging markets. Because neither the users nor the Internet service providers changed the administrator name and password for the routers and the devices are set to be remotely accessible, attackers were able to create a script that spread rapidly among the routers so they could be linked together in a botnet, according to the report written by Imperva’s website security division Incapsula.
“The problem here is that by default home routers are not provisioned for an individual to know to change the username and password,” Tim Matthews, vice president of marketing for Imperva’s Incapsula group, told eWEEK. “Most people couldn’t be bothered to log into the router and change it.”
Incapsula began researching the botnet when attackers used it to level denial-of-service attacks against “several dozen” of its customers, using more than 40,000 Internet addresses. When the researchers realized the same make of router was being used in the attacks, they assumed a common firmware flaw had been used to compromise the routers. After analyzing the malware files, they realized that the attack just used default administrator credentials.

The company’s researchers estimate that tens of thousands of routers, connecting through more than 1,600 Internet service providers, had been compromised to make up the botnet. More than 85 percent of the infected routers were located in Brazil and Thailand, the report stated. The command-and-control servers are located in China and the United States.

“Given how easy it is to hijack these devices, we expect to see them being exploited by additional perpetrators,” the report stated. “Even as we conducted our research, the team documented numerous new malware types being added, each compounding the threat posed by the existence of these botnet devices.”
The program used to seek out and infect devices had worm-like capabilities. The attackers did not just scan for vulnerable routers and infect them. Rather, a compromised router automatically began scanning for new hosts inside its current network.
While ten thousand compromised routers can create a significant flood of data, Incapsula argues that the problem is likely much worse. Hundreds of thousands, or even millions, of routers likely have similar problems, Matthews said.
“What we see here is a widely available resource for attackers,” he said.
Attackers have most recently focused on compromising servers and using the machines for denial-of-service attacks, but if residential routers are easy to infect, then attackers will adapt.
“With home routers, they can make it up in volume,” he said.